Electroluminescence Mechanism of ZnS:Cu Composite Coatings Under High-electric-field

Various kinds of insulation defects are inevitably generated during the assembling and operation of electric transmission and transformation equipment. electroluminescence materials could be introduced into insulation systems to visually display the high-electric-field regions, which realizes the self-detection of insulation defects. In this work, the electroluminescence mechanism of ZnS:Cu composite coatings under high-electric-field is investigated. By measuring the luminance distribution, discharge current and surface charge distribution of rod-plane electrode in transformer oil and air, the electroluminescence properties without and with discharges are explored, respectively. The results indicate that the electroluminescence of ZnS:Cu composite coating comes from charge polarization luminescence without discharge and gas discharge induced luminescence under high-electric-field. The distribution of charge polarization luminescence is closely correlated to the electric field. When the discharge is initiated, the generated positive and negative charges are deposited on the coatings and migrate to ZnS:Cu particles, which form the excitons and thereby produce luminescence by the radiative transition. The basic electroluminescence mechanism of ZnS:Cu composite coatings is derived by experimental results, which could guide its application in qualitative characterization of electric filed and self-diagnosis of insulation defects. ©2023 Chin.Soc.for Elec.Eng.